科创中国

A complex of gabbro (with metamorphic pyroxenite xenoliths)-gabbroic diorite-granodiorite was recently discovered in Tongxunlian, Xilinhot city, Inner Mongolia. Zircon U-Pb isotopic dating showed that the gabbro and the granodiorite were formed ca. 319±1Ma and ca. 318±1Ma respectively, indicating that emplacement of the composite rocks occurred in the late Carboniferous. Positive ε_Hf(t) values of +12.0 to +14.1 and two-stage model ages (T_DM2) of 418 to 537Ma of these rocks are similar to the age of formation of metamorphic pyroxenite (560Ma, based on Sm-Nd isochron dating) and suggest that the rocks were derived from depleted lithospheric mantle (metamorphic pyroxenite). Our findings revealed that all of these calc-alkaline and metaluminous intrusive rocks formed from the fractional crystallization of comagmatic evolution in an island-arc setting. Moreover, the gabbro-gabbroic diorite in the study region was characterized by a low TiO₂ content, a slight deficit of Nb, a surplus of Ta, and relatively low LREE/HREE ratios. Along with a relatively high Zr/Y ratio (4.0 to 5.6), these characteristics indicate that the rocks may have been formed by melting of the mantle wedge via metasomatism. Combination with other features of the rocks indicates a two-episode tectonic model: we conclude that first, the fluid and Si-rich melt metasomatism caused partial melting of the enriched lithospheric mantle, and these influences were then stored in the mantle and second, slab breakoff resulted in upwelling of the upper mantle's soft fluid (stratum), which melted the enriched mantle of the lithosphere and formed the basaltic magma of the gabbro-gabbroic diorite. This study provides new geological evidence to support the Neoproterozoic subduction between the Paleo-Asian Ocean plate and the Xilinhot microcontinent.

Wenxiao Zhou;术才 李;Mengchun Ge;Dong Fu;Xinna Chai;Yang Yu

Geological Journal

2016-1-1

In order to obtain the mechanic characteristics of casing joint on the square steel tube confined concrete supporting arch, the bending behavior pattern of casing joint was analyzed. The critical hinge-rigid switch angle was calculated and discussed, and based on which the criterion of casing joint hinge-rigid pattern was proposed. A numerical test of casing joint pure bending was carried out. The typical 4-step overall process curve of confined concrete casing joint was obtained, and the cause of OA stage of the curve and its influence on bending bearing capacity was analyzed. Also the mechanical behavior pattern and mechanical properties were obtained. At the same time the characteristics of original curvature and other different parameters (concrete strength f_cu,k, length l, thickness t, gap δ, etc) on different mechanical parameters such as ultimate bending moment M_ue, critical curvature increment and equivalent bending rigidity(K_i, K_s)were discussed, and the parameter design idea of casing joint on the square confined concrete (SQCC) arch was proposed.

Weiteng Li;Qi Wang;术才 李;Ning Yang;Xin Wang;Xing Shao

Zhongguo Kuangye Daxue Xuebao/Journal of China University of Mining and Technology

2015-11-1

A dynamic consolidation model of double layered foundation of saturated soil and unsaturated soil is proposed. Mechanism of dynamic compaction treating on double layered foundation is studied by the model. On the base of the mechanism a new technology called soil-mound dynamic consolidation can be applied to treat the ground of saturated silt and silty clay with high groundwater level. The water-pore pressure test, static cone penetration test, settlement plate test are applied to evaluate that of the new technology with different construction parameters. The treatment effect is more remarkable than that of plastic drain-dynamic consolidation.

Yao Xu;术才 李;Xiao Zhang;Bin Yan;Chunmei Zhu

2011

Phase III of Harbin Metro Line #1 was constructed in low to medium plasticity silty clay. In the primary design, forepoles with a spacing of 0.8 m were used as pre-support. However, it was found in the practice that the drilling rate was low and the grouting diffusion range was limited when the water content was low in the silty clay. In order to determine the optimum forepole spacing in relation to water content of the silty clay subject to tunnelling, a method combining laboratory tests, numerical simulations with field monitoring was developed in this study. A series of laboratory tests were performed to relate the deformation and strength parameters of the silty clay with water content. The silty clay has been sub-classified according to liquid index the mechanical parameters at different sub-classes were suggested. The parameters were used in numerical simulations for the determination of the optimum forepole spacing for tunnels in soil mass with different water contents. Field monitoring was performed to calibrate the water content-dependent deformation and strength parameters used in the numerical simulations. Numerical simulations were performed to obtain the ground surface settlement, crown settlement and steel rib axial stress for the cases without pre-support, and with forepores in different spacing. Finally, a scheme for the determining the optimum forepole spacing in relation to water content of the silty clay was obtained. In the scheme, for the silty clay with liquid limits in the range of 0.05–0.20, the tunnel could maintain stability without forepoles for the silty clay with liquid limits in the ranges of 0.20–0.45, and 0.45–0.8, the tunnel could maintain stable with forepoles in spacing of 0.8 m and 1.6 m, respectively. This scheme was used in both the phase III of Harbin Metro Line #1 and Harbin Metro Line #3. The practices proved that the scheme was applicable to the pre-support for safe and economic tunnelling in the low to medium plasticity silty clay for Harbin Metro construction.

Zhechao Wang;Wei Li;术才 李;Wenge Qiu;Wantao Ding

Tunnelling and Underground Space Technology

2018-4

The combined propagation and interaction of pre-existing cracks are important factors for rock mass overall instability and failure. Many experiments have been conducted to investigate the influence of 3D internal crack on strength and crack propagation pattern in rock samples. However, several issues like the influence of cracking spacing on the cracking pattern of rock subjected to tensile stress remain unsolved. In this study, a new type of rock-like material and a novel direct tensile apparatus are developed. Uniaxial tensile experiments on artificial rock samples containing two internal elliptical cracks with different crack spacing are conducted. Experimental results indicate that the tensile stress-strain curves of different samples exhibit 4-stage behaviors. Crack spacing has obvious influence on the tensile peak strength (σ_P) of sample. σ_P decreases gradually with the increase of crack spacing when 0<d/2a≤1 (where d represents crack spacing, and 2a is the length of crack), but increases as crack spacing increases when 1<d/2a≤1.25. Under tensile stress, wrapping wing crack and secondary crack initiate sequentially near the front of long axis of each pre-existing crack, and the lateral growth initiates near the front of short axis.

L. Yang;Y. Jiang;B. Li;术才 李;M. Li

2010

A rock-like cement mortar material with high strength, convenient matching, and high brittleness isadopted to conduct compression tests and the multi-joint specimen is prepared by pre-embedding PVC sheets. The expansion and penetration processes of multiple joints are studied, and the impact of joints on rock mechanical properties is discussed. The test results show that the specimen failure process is mainly divided into four stages, that the jointed specimen and complete specimen have different crack initiation positions and significantly distinct failure modes, that the weakening effect on rock strength is connected with the number of joints, and that the specimen's post-peak deformability is enhanced. The discontinuous deformation analysis for rock failure (DDARF) method is adopted to conduct numerical simulation on the preceding test. The simulation results agree well with the test.

Chenglong Zhao;Weishen Zhu;术才 李;敦福 张

Energy Education Science and Technology Part A: Energy Science and Research

2014

By using the real-time CT (computerized tomography) unit with specially developed water-injection loading apparatus, several failure tests of single-crack concrete specimens with interstitial water pressures under triaxial compression were conducted. The complete failure process: the closure, the initiation of new damage area, the secondary closure, as well as the crack propagation of the specimens were simulated. The CT images at each stage, the CT numbers and the comparison among different sections in the specimens were obtained. Based on the observed results, the role of compressive pressure in damage and propagation of hydrous crack can be intuitively revealed, and the characteristics of damage-evolution of cracks in brittle material can be better understood at meso-level.

术才 李;W. S. Zhu;Y. Y. Jiao;H. Jian

Key Engineering Materials

2006

This paper puts forward a damage-fracture mechanical model and a damage-rheology mechanical model for the jointed rock mass of the high slopes in the ship lock area of Three Gorges Project. These two models are used to analyze the slopes' stability. A comparison of the computed displacements at numbers of points on the slope surfaces with the results from 3-D analysis is also made. In addition, some computing results are compared with the in-situ measured ones, showing that the model proposed is basically reliable.

W. Zhu;术才 李;庆松 张;X. Qiu

Key Engineering Materials

2006

The Hegenshan ophiolite is located in the northern part of Xing' an Mongolia orogenic belt. It consists of a complete rock assemblage including peridotite, cumulate rocks and mafic lava associated with radiolarian cherts. The formation age of the Hegenshan ophiolite has long been controversial, which makes a lot of troubles in dividing the tectonic evolution stages. Zircon U-Pb isotope chronology studies have shown that the crystallizing age of the gabbro diorite (341 ± 3Ma) and basalt (359 ±5Ma) in Hegenshan ophiolite are in the early Early Carboniferous and the peak age of the inherited zircons in basalt is early Late Devonian (375 ±2Ma). These inherited zircons in basalt are short prismatic and angularity with wide, patchy or planar growth zones which display the characteristics of basic magmatic zircons. All of these indicate that the oceanic crust already formed during early Late Devonian. The pyroclastic rocks of the Upper Carboniferous Gegenaobao Formation are unconformity with the Hegenshan ophiolite. The age of the tuff in this formation is 323 ±3Ma which support the minimum age for the emplacement of Hegenshan ophiolite. So we suggested that the age of the Hegenshan ophiolite is Late Devonian to Early Carboniferous and the emplacement time is Late Carboniferous. While the ages of some mafic dikes in Hegenshan ophiolite are Early Cretaceous (132 ± 1 Ma, 139 ±3 Ma and 120 ± 1 Ma). They contain a lot of inherited zircons (144 ± IMa ∼ 2698 ±25Ma). The peak ages of these inherited zircons closely respond the complex magma and tectonic events before Early Cretaceous in the northern Xing ' an Mongolia orogenic belt. These mafic dikes might form in the extensional environment during the Mesozoic but not the Early Carboniferous ophiolite. Combined with previous achievements as well as temporal and spatial distribution characteristics of regional strata and magmatic rocks we built the tectonic evolution of the northern Xing' an Mongolia orogenic belt during the Late Paleozoic. We suggested that the Erenhot and Hegenshan area was in the denudation stage in the Early Devonian and the continental crust expanded to form the oceanic basin in the Middle Devonian, the basin continued to expand and formed the oceanic crust in the early Late Devonian and then the crust began to subduct northward in the late Early Carboniferous and accreted to the Siberian continental margin which resulted in the gradually closing of the ocean basin during the Late Carboniferous, and most emplaced ophiolites were unconformity covered by the volcanic rocks of Late Carboniferous. The Hegenshan ophiolite is the residue of this oceanic lithosphere.

Bo Huang;Dong Fu;术才 李;Meng Chun Ge;Wen Xiao Zhou

Acta Petrologica Sinica

2016

With the increasingly urgent demand of underground energy reserves, more and more underground salt rock gas storages are put into use. Underground salt rock gas storages are adopted around the world, because of their good features. Therefore, it is very significant to study the safety and stability of underground salt rock gas storage in operation period. During operation period, gas storage cavity is under time-varying pressure of the inner gas. At the same time, the storage has some risks because of objective uncertainties and it is difficult to study the storage risks with deterministic method. Jintan underground salt rock gas storage is taken as an example. The time-varying pressure curve is created and the transient mechanics method is used to study the long-term rheology of the underground salt rock gas storage. Based on stochastic mechanism method, the failure probability variation of the underground salt rock gas storage during operation period is obtained by ANSYS-PDS with taking the volumetric shrinkage as the control criterion. Calculations show that the displacement of the cavity increases in a wavelike form under the time-varying pressure of the inner gas and the amplification reduces gradually. The failure probability shows this variation: it grows slowly first and then grows fast gradually and it slows down and is stabilized finally. The influence of velocity of gas recovery and injection on the gas storage stability is discussed. Reducing the velocity of gas recovery and injection can suppress the volumetric shrinkage and improve the stability of gas storage. It is meaningful to the risk analysis and assessment of other similar underground salt rock gas storages.

超 贾;Peng Li;强勇 张;术才 李

Yantu Lixue/Rock and Soil Mechanics

2012-11